In a typical toner image reproduction machine, for example an electrostatic image forming apparatus, an imaging region of a toner image bearing member, such as a photoconductive member, is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is irradiated or exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document.
After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering to carrier granules. The toner particles are attracted from the carrier granules to the latent image, forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet. Residual toner particles, additives and/or debris remaining on the photoconductive surface following image transfer as above are then removed by a cleaning apparatus in order to prepare the surface for forming another toner image.
Primary cleaning systems were developed to remove residual toner from the photoconductive member prior to the next image development procedure. Such primary cleaning systems may include one or more rotating electrostatic brushes, cleaning blades, electrostatic air cleaners, vacuum systems, and other similar systems used singly or in combination. For example, a rotatable brush is mounted in interference contact to the photoreceptor surface to be cleaned, and the brush is rotated so that the brush fibers continually wipe across the photoreceptor. Electrical bias applied to conductive brush fibers aids in removing and transporting cleaned material away from the photoreceptor surface. In order to reduce the dirt level within the brush, a vacuum system is provided which removes residual toner and toner agents from the brush fibers and exhausts the toner and toner agents from the cleaner.
However, experience has shown that certain agglomerations of toner particles and other materials can stick to photoreceptors or other charge retentive surfaces sufficiently to resist removal by primary cleaning systems.
In response, secondary cleaning systems were implemented in some systems. Such secondary cleaning systems may include a relatively hard cleaning “spots blade” located downstream from the primary cleaning system for the purpose of shearing agglomerations that resist initial cleaning away from the imaging surface. The spots blade may be engaged and disengaged with the imaging surface. For example, U.S. Pat. No. 4,158,498 issued Jun. 19, 1979 and entitled “Blade Cleaning System for a Reproducing Apparatus” discloses a reproducing apparatus that includes a blade cleaning system for removing residual material from an imaging surface. The blade is arranged for movement between a first position wherein an edge thereof engages the imaging surface to remove the residual material, and a second position wherein the edge is spaced from the imaging surface.
Contact cleaning devices, for example, spots blades for cleaning the photoconductive member, may scratch and abrade the surface where there is insufficient lubrication at the interface between the blade and the surface. Thus, it is known to lubricate the image forming surface because lack of sufficient lubrication to the edges of such blades may result in scratching and abrasion of the image forming surface. Lubrication may be provided in the form of residual, or specifically placed, toner substances and/or additives.
U.S. Pat. No. 5,463,455 issued Oct. 31, 1995 and entitled “Method and Apparatus for Adaptive Cleaner Blade Lubrication” discloses an adaptive cleaner blade lubricating system for electrostatic printing machines. The amount of residual toner available to lubricate a cleaner blade is calculated based on the density of the transferred image. A band of toner is deposited in an inter-document gap, or zone (“IDZ”), in selective widths so as to provide an adequate amount of toner to lubricate the cleaner blade across the full width of the photoreceptor. The lubrication band may be variable or may be a constant width with the frequency of placement of the band determined based on average image density for a group of documents.
U.S. Pat. No. 7,362,996 issued Apr. 22, 2008 and entitled “Cleaning and Spots Blade Lubricating Method and Apparatus” discloses a system using a toner patch in the IDZ in combination with switching a cleaner brush bias from a nominal high voltage to near zero voltage to reduce cleaning efficiency.